Foam plastic egg carton



p 30, 1969 R. B. GAYLOR, JR 3,469,764

FOAM PLASTIC EGG CARTON Filed Jan. 7, 1969 I mvsw'roa [a e/er 5. GAYM/C .12.

Uted States Patent O US. Cl. 229-44 8 Claims ABSTRACT OF THE DISCLOSURE A foam plastic egg carton is provided which is formed from a continuous sheet of foam plastic material and comprises a cover and tray portion connected by an integral hinge. The cover portion has therein bossed areas containing apertures to serve as locking means and terminates in a substantially horizontal flange. The tray portion also terminates in a substantially horizontal flange and contains a longitudinal partition and transverse partitions, with separating posts being formed by the intersection of the partitions to form egg receiving cells. A plurality of the transverse partitions terminate in outward and upwardly extending catch posts in the side opposite the hinged portion of the tray, the posts terminating in substantially horizontally extending lips which, when the cover is super-imposed upon the tray portion, cooperate with the lower edge of the apertures in the tray portion to maintain the cover in closed position.

BACKGROUND OF THE INVENTION The insulating and cushioning properties of foam plastic material is well known. The application of this excellent material in egg cartons has been deterred because of the lack of a suitable locking mechanism which would enable the easy opening and closing of a container and yet could be formed in one thermoforrning operation. Locking mechanisms are common in the conventional pulp car tons but the fragile nature of foam plastic materials has heretofore caused them to be unsuitable for use with looking mechanisms which have been usable with the conventional molded pulp cartons. Examples of some of the locking mechanisms that have been proposed for foam plastic cartons are the intricate devices described in US. Patents 3,337,110, 3,337,854, and 3,391,845, employing locking flanges and tabs.

A locking mechanism using a latch post closure is described in US. 3,217,963. This device is unsuitable for foam plastic material because of the difliculty encountered in thermoforming such a locking device, with its posts, and also because of the easy breakage of such posts in view of the fragile nature of foam plastic material. Although suitable for pulp cartons, such a mechanism would be of little value in locking of a foam plastic lid to a bottom section, because of the need to force the relatively thin cover portion outwardly or the thin posts inwardly to release the fragile lid.

The object of the present invention is to provide a foam plastic egg carton which has a novel and reasonable locking mechanism readily adapted for use with conventional egg packaging machinery and also suited to the many openings and closings necessitated for consumer use.

SUMMARY OF THE INVENTION In accordance with the present invention, a unitary egg carton is formed from a single sheet of foam plastic material and comprises a tray and cover portion, hingedly connected. The cover portion has a top wall and four upwardly and outwardly extending walls which terminate in a horizontal flange, the wall opposite the hinged connection having a plurality of outwardly extending bosses, the bosses having therein apertures which serve as part of the novel locking means. The tray portion comprises a bottom wall, a pair of end walls and side walls, which are outwardly and upwardly extending, terminating in a horizontal flange, a longitudinal partition extending between the end walls and a plurality of transverse partitions which, at the intersection with the longitudinal partition, form separating means and provides egg cells for the receiving and cushioning of eggs. A plurality of the transverse partitions terminate in outwardly and upwardly extending catch posts, these catch posts extending above the flange opposite the hinged connection and terminating in horizontally disposed lips which are positioned inward from the outer edge of the flange and, when the cover portion is positioned on the tray portion in locked position with the cover and tray flanges adjacent each other, the lips contact a portion of and are adjacent to the lower edge of the aperatures in the cover portion to secure the cover portion in closed position and yet provide ready opening and closing of the container without danger of breakage of the contents or the carton.

The objects and novel features of the invention are described by the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are not intended as a definition of the invention, but are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawing wherein like parts are marked alike:

FIGURE 1 is a top plan view of the egg carton of the invention in open position.

FIGURE 2 is a front elevational view of the egg carton in closed position.

FIGURE 3 is a sectional view taken along lines III- III of FIGURE 1, with the lid in closed position shown in phantom.

DETAllED DESCRIPTION Referring now to FIGURE 1, there is illustrated in open position, a foam plastic unitary egg carton 11 whose cover portion 13 and tray portion 15 are connected by an integral hinge 17. The egg carton would be formed from foam plastic sheet material in a mold in this open position and then removed therefrom.

The cover portion 13 comprises a top wall 21 and four upwardly and outwardly extending walls 23. The walls '23 terminate in a substantially horizontally extending flange 25 around the periphery of the cover portion. The wall 23, opposed the hinged connection 17, has therein a plurality of outwardly extending bosses 27 extending from the flange 25 a distance towards the top wall 21. In the bosses 27, there are positioned apertures 29, the lower edge 30 of the apertures being spaced a distance from the flange 25. The bosses 27 and apertures 29, herein illustrated as of substantially rectangular configuration may be of semicircular, eliptical or other configuration if desired, with the lower edge thereof spaced from said flange.

In order to provide additional strength for said cover portion and permit stacking of the cartons without danger of breakage, a plurality of ribs 61 are provided, extending from the flange 25 a distance towards the top 21. These ribs strengthen the cover and absorb some of the vertical pressures exerted on stacked cartons and permit the use of foam plastic sheet material in the formation of lightweight egg cartons.

The tray portion 15 of the carton comprises a bottom wall 45, a pair of upwardly and outwardly extending end walls 33, and a pair of upwardly and outwardly extending side walls 35 terminate in a substantially horizontally extending flange 37 around the periphery of the tray portion 15. One of the side walls 35' of the tray portion 15 is hingedly connected to the cover portion 13 by means of integral hinge 17.

Extending between the end walls 33 of tray portion 15 is a longitudinal partition 41 that separates the tray into equal half portions while a plurality of transverse partitions 43 extend between the side walls 35. Longitudinal partition 41 and transverse partitions 43 intersect to form separating posts 45 and provide a plurality of egg receiving and cushioning cells 47.

As a portion of the novel locking mechanism of this invention, a plurality of the transverse partitions 43 terminate as upwardly and outwardly extending catch posts 51 which extend above the flange 35 opposite the hinged connection 17 of the tray. These catch posts 51 terminate in a horizontally disposed lip 53. These lips are spaced 8. distance from the outer edge 55 of the flange 37 of the tray portion 15. The catch posts 51 are formed from the edge of the sheet material and extend to a position spaced inward from the outer edge 55 of flange 37.

In accordance with this invention, the cover portion 13 is swung upwardly and over into superimposed position on the tray position 15, along integral hinge 17 to close the egg carton. The cover portion 13 is then forced downwardly whereupon the lip 53 of the catch posts 51 contacts the bossed areas 27 of the cover portion. The application of a gentle closing pressure forces the front of the cover portion 13 downwardly and the lip 53, because of the resiliency of the foam plastic material, passes along the bossed area and is secured within said apertures 29. The lip 53 extends into the aperture 29 and is adjacent to the lower edge 30 of the aperture. In closed position, the flange 25 of the cover portion contacts the flange 37 of the tray portion and thus seals the carton.

To open the carton, the cover portion 13 can, by gentle lifting pressure, be forced upwardly and the lip 53 will be released from the aperture 29. Since the lip 53 does not extend any substantial distance through the aperture 29, easy opening and closing of the container without exerting pressures inwardly on the tray portion 15 or outwardly on cover portion 13 is provided, with lessening of the danger of breakage of the eggs contained within the carton when in use.

The contact of flange 25 and flange 37 is better seen by reference to FIGURE 2, where the cooperation of catch posts 51 and lip 53 of tray portion 15 with the lower edge 39 of the apertures 29 in bossed areas 27 of the cover portion 13 is seen from a front view.

The cooperation of lip 53 with the apertures 29 is shown in detail in FIGURE 3. The lip 53 extends into aperture 29 and terminates adjacent the outer edge of the lower edge 30 of the aperture.

Because of the fact that resiliency and strength are necessary in the egg carton, the preferred material for construction of the novel egg carton is foam polystyrene sheet material. Other usable foam plastic materials include impact polymers such as styrene-butadicne copolymer foams and the like. To provide the required resiliency and strength, the foam plastic sheet material must have a basis weight range of between 30-75 pounds per 1,000 square feet. Basis weight, as used herein, is determined by multiplying the thickness of the sheet material in mils by the density of the sheet material in pounds per cubic foot and then dividing this product by the numeral 12. As an example, a polystyrene foam sheet having a 60 mil thickness and a density of pounds per cubic foot has a basis weight of 50, i.e.

The egg carton, which can be designed to hold twelve, six, or other quantities of eggs would be dimensioned to suit the end use thereof. The carton can be formed by using conventional techniques such as heat forming, vacuum forming, etc. Suitable techniques are known in the art and are exemplified by those described in Koppers .4 Technical Bulletin, Thermoforming Foam Polystyrene and Polystyrene Laminates, Bulletin C-9-273, chapter 40, Apr. 15, 1952.

The foregoing has described a novel foam plastic egg carton that can be formed from a sheet of foam plastic material in a single forming step. The carton provides a novel locking means comprising catch posts that terminate as horizontally disposed lips in the tray portion which cooperate with apertures provided in bossed areas of the cover portion. Ribs in the cover portion give added strength to the carton and provide a lightweight carton that can be stacked without danger of breakage of the carton or its contents.

What is claimed is:

1. A unitary egg carton formed from expanded foam plastic sheet material comprising a cover portion and a tray portion hingedly connected,

(a) said cover portion having a top Wall and four upwardly and outwardly extending side walls, each of said side walls terminating in a first substantially horizontally extending flange, a portion of said flange extending from one of said side walls forming a hinge, the side wall opposite said hinge having therein a plurality of bosses extending outwardly therefrom and extending from said first flange a distance towards said top wall, said bosses having therein apertures with the lower edge of said apertures spaced from said first flange;

(b) said tray portion having a bottom Wall, a pair of upwardly and outwardly extending end walls, and a pair of upwardly and outwardly extending side walls, said side and end walls terminating in a second substantially horizontally extending flange, with a portion of said second flange extending from one of said side walls hingedly'connected to said cover portion, a longitudinal partition extending between said end walls, and a plurality of transverse partitions extending between said side walls, said longitudinal partition and transverse partitions intersecting at separating posts to form a plurality of egg receiving and cushioning cells;

(c) a plurality of said transverse partitions terminating in outwardly and upwardly extending catch posts, said catch posts extending above said second flange opposite said hinge and terminating in a horizontally disposed lip positioned inward from the outer edge of said second flange, whereby, when said cover portion is folded along said hinge onto said tray portion to cover the same, with said first and second flanges adjacent each other to assume a locked position, each of said lips contacts a portion of the lower edge of a respective aperture to maintain the carton in locked position.

2. The carton of claim 1 wherein said foam plastic sheet material has a basis weight of 30-75 pounds per 1,000 square feet.

3. The carton of claim 1 wherein said foam plastic sheet material is foam polystyrene.

4. The carton of claim 1 wherein said cover portion has a plurality of ribs extending from said first flange a distance towards said top.

5. The carton of claim 4 wherein said ribs are substantially planar with said transverse partitions and said horizontal partition of said tray portion when the carton is in closed position.

6. A unitary egg carton formed from a continuous sheet of foam plastic having a basis weight of 30-75 pounds per 1,000 square feet comprising:

(a) a cover portion having a top and four upwardly and outwardly extending walls that terminate to form a horizontally extending flange;

(b) a tray portion having a pair of upwardly and outwardly extending end Walls and a pair of outwardly extending side walls, said end and side walls terminating in a second horizontally extending flange;

(e) an integral hinge, comprising a fold line in said continuous sheet, interconnecting said cover and tray portions;

(d) said cover portion having in the wall opposite said hinge, outward bosses extending from said first flange a distance towards said top wall, said bosses having apertures therein with the lower edge of said apertures spaced from said first flange;

(c) said tray portion having a longitudinal upwardly extending partition and a plurality of transverse upwardly extending partitions, said longitudinal and transverse partitions intersecting to form separating posts, and a plurality of said transverse partitions terminating in outwardly and upwardly extending catch posts extending above said second flange opposite said hinge, said catch posts terminating in a horizontally disposed lip positioned inward from the outer edge of said second flange;

(f) whereby when said cover is folded along said hinge onto said tray, with said first and second flange in contact with each other, each of said lips of the tray portion contacts a portion of the lower edge of a respective aperture of the cover portion to maintain the carton in closed position.

7. The carton of claim 6 wherein said foam plastic is polystyrene.

8. The carton of claim 6 wherein said cover has a plurality of ribs extending from said first flange towards said top.

References Cited UNITED STATES PATENTS 3,217,963 11/1965 Alsman 2292.5 3,276,656 10/1966 Hartmann et a1 2292.5 3,298,594 1/ 1967 Makowski et a1. 229-45 3,326,443 6/1967 Burkett 2292.5 3,362,605 1/1968 Bixler 2292.5 3,372,854- 3/1968 Marcus 2294.4 3,391,845 7/1968 Bessett 229- DAVIS T. MOORHEAD, Primary Examiner US. Cl. X.R. 2292.5 

